A conventional bicycle front suspension device 80 is disclosed in FIG. 6A and is controlled by a cable 81 which is connected to a switching device attached on handlebar of the bicycle. The cable 81 is wrapped around to a cap 82 which is connected with a torsion spring 821 so as to return the cap 82 to its original position, a shaft 85 is fixed to the cap 82. A tube 84 is received in the steeter tube which is movably inserted in a front fork and the handlebar is fixed to a top of the steerer tube. A first through hole 841 is defined through a wall of the tube 84. A seal member 83 is inserted in a top end of the steerer tube and the tube 84 extends through the seal member 83. The shaft 85 is rotatably received in the tube 84 and includes a second through hole 851 which is rotated to an open position where the first and second through holes 841, 851 are in communication with each other. Hydraulic oil is received in the steerer tube and when the suspension device 80 is set to an operative status, the shaft 85 is rotated to the open position such that the hydraulic oil enters the second through hole 851 and flows out from the first through hole 841 to allow the relative movement of the steerer tube and the front fork. As shown in FIG. 6B, when the user wants to lock the front suspension device 80, he or she simply pulls the cable 81 to rotate the cap 82 and the shaft 85 to rotate the second through hole 851 from the first through hole 841. The hydraulic oil then cannot flows through the two through holes 841, 851 so that there will be no relative movement between the steerer tube and the front fork. It is experienced that it requires a lot of force to rotate the shaft 85, especially for the limited diameter of the cap 82 which generates only a short arm of force to rotate the shaft 85.
The present invention intends to provide a bicycle front suspension device which is optionally adjustable in various damping stages and includes a simple structure and can be positioned to match with different types of brake systems and orientation of the cable.